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Heavy Cruiser - Bombardment

Before presenting this design attempt, I'll expound a bit on the intended mission behind the ship.

Firstly the ship was inspired by the relative low importance of surface action in the Sino-Chosen war and the corresponding importance of land combat.

The ship is intended to operate in close coordination with the army on the tactical level. In short, the ship is a massive artillery piece with the ability to reach far into enemy territory, fire rapidly and reliably. The advantages of such a system is clear, most large artillery pieces are immobile, which is not the case with a ship. The disadvantages are also clear, large investment of production capabilities, limited reach due to requirement of being in water. The loss of accuracy at long range is less of an issue than appearances presume given that artillery itself is not entirely accurate, it is firing at a non-moving target, and the ship itself should not be moving.

Hence these disadvantages form the basic requirement of the ship: 1) Low displacement, 2) Long range, 3) A large C3I system
For the 2nd, I choose to aim for a 380mm/56 gun firing a 495kg shell (the same weight as the the coastal artillery version of the Bismarck's gun). The Bismarck edition reaches 60km at 52 degrees firing the 495kg shell, this version reaches ~65km at 50 degrees firing the same shell. By comparison, other guns of from 40.6cm - 46cm have ranges in the vicinity of 38-42km.

This range means it's ability to reach targets is quite great. It can:

Cover the whole of Jeju Island from one position, 30km off coast.

Reach targets in the 66% of the Philippines.

Reach targets anywhere in Taiwan.

Reach targets in 66% of Korea (Seoul and Pyongyang can be reached from 30km off coast)

Reach targets anywhere in Japan

Cover 50% of the Zheijiang Peninsula from the port of Haikou in Hainan

Reach targets anywhere in Denmark

etc. etc.

The other issue is the threats such a ship would face.

Submarines

Surface Action

Aerial Assault

The issue of submarines can be solved by putting the ship in a battle group with destroyers which will make it very hard for a submarine to approach (given the group will be moving at slow speed or still when conducting a fire mission).The issue of surface action can be solved one of two ways: having heavy surface guns and thick armor to engage enemy surface ships or having higher speed than enemy surface ships to avoid them.The issue of aerial assault can be solved one of two ways: having a CAP to protect it or having a very heavy anti-air battery.

For the issue of surface action, the latter choice is much better given our goal is to have a low displacement ship. The former choice would result in a battleship-sized vessel, which is far too much investment in a niche role.For the former choice in aerial assault, the CAP can be provided either by an escort carrier or by the ship having it's own air complement. Neither choice is ideal, the former for risking another capital ship and the latter for all the AVGAS, space, etc. requirements that would force upon the design. Hence it would be better to have a very heavy anti-air battery.

I also made another version in which 2 380mm barrels were swapped out in exchange for trimming off 2,500 tons and an increase of 2 knots. (A 2x2x380mm ship at 19,000 tons normal with speed of 36 knots)

A nice design. The main thing I see being a problem is that a ship this large should incorporate a TDS. And if the ship is going to be used for shore-bombardment a floatplane for spotting would be handy.

A ship on less than 80ft of beam isn't going to have an effective TDS even if the weight and space is allocated towards it. It simply doesn't have the width to adequately absorb such shock. If we were to demand such a ship have a TDS, then there is no way the beam is wide enough to support the triple 380mm. This would require the ship to displace more tonnage which it then has to either sacrifice strength for speed or heavier armor.

As for the floatplane recommendation, my line of thought was as follows: The ship is not meant to fire independently by in coordination with the army. Hence, C3I and the large communications suite. The forward observer has many tools at his disposal to deal with identified threats, this ship's barrage is meant to be one of them. Hence there is always be someone else marking the target to fire at. In that situation, having a floatplane on board would be both a hazard (due to catapult & plane fuel) and a waste of space/weight. ... Or so goes my line of reasoning.

That said, cutting tonnage is always a good enough reason to go for a third pass. By removing one of the main guns and thinning out the armor, I managed to shrink the ship to a 16,500 ton @ 37.5 kt package, a reduction of 5,000 tons, with is a lot more palatable for tonnage-conscious folks. The increased speed also means there are no ships that can catch it.

My biggest concern with the designs posted thus far is that the beam feels inadequate for a triple 15" turret - I'd have looked for about 90-100' beam at least, though I'd have accepted possibly as low as 80' for a twin turret. Are there any historical design proposals you looked at that had narrower beam?

I think that your target reach figures does not take into account the complete suicide aspect of taking that ship so close to shore or into fairly restricted areas such as the Inland, Bohol, Visayan or Sibuyan Seas, or Kattegat. I think that the number of AA guns and the size of the CAP will have to be massive. Due to the proximity to the coastline, you can expect every plane to be heading your way.

To get at everything in Denmark, you'd have to go through fairly narrow straits where even people with portable rocket launchers would probably be shooting at your ships. Other nasty surprises in such traps would be shore mounted torpedo tubes, massive amounts of MTBs and midget subs. I can also see truck-mounted rockets being fired at those ships as well. If you have 100 MTBs and midget subs in that trap, each carrying 2 torpedoes, you'll have 200 torpedoes in the water and only two are needed to sink that cruiser (and due to the confined space, I would think that quite a few escort ships will bite the dust as well).

To employ such a vessel would demand prior control of the air and sea surrounding the intended target area, obtained by more conventional means. If control of the air and sea have already been obtained, such a vessel is rather superfluous.

I will break my response into two "sections". The first section (this one) will answer the issues raised by others regarding the design and hopefully resolve them. It will engage mostly on the technical level, that is whether something can be done, not whether it should be done. The latter section will be comprised of my response to the criticism of the design. This is what I should and will do which exists outside of technical details. The purpose of the first section is to provide informative discussion, not to be antagonistic to anybody and the points they raise. However, given that these designs can be seen as pushing the envelope, rest assured I will modify the designs themselves to the common realm of acceptance. That is the second section.

Quoted

My biggest concern with the designs posted thus far is that the beam feels inadequate for a triple 15" turret - I'd have looked for about 90-100' beam at least, though I'd have accepted possibly as low as 80' for a twin turret. Are there any historical design proposals you looked at that had narrower beam?

I have quite some reason to doubt the need for 90-100' beam. I'll expound on that: The requirement of such beam is mostly a function of the need for TDS space as well as the number of barrels, not of the gun diameter itself.

If we look at the barbette diameter data on historical guns that was once posted on Warships1 for the UK RN by Tony D:

From this data we can guess an RN Three-gun 15" gun will have a barbette diameter of ~35ft which is not too far from that of the KM 11" triples which had diameters of 33.46ft (10.2m). The KM did have much more spacious turrets compared to other navies. The point I am making is that a beam about the same size as the Deutschland-class will hold triple 11'' (280mm) just as well as triple 15" (380mm). Of course, if you have very spacious turrets then you will need more beam by this metric, but that's a design choice, not a technical one.

I'll give some similar beams in historical designs and design studies:
The Deutschland-class mentioned previously had a beam of ~21.7m or ~71 ft and held triple 11"s. If we look at their cut-out, we see the beam at the turrets are quite a bit more thin than that of the beam at amidships which is where it is 71ft wide.

The early pre-dreadnought era is also has some for historical similarities given it was a period in which there was no torpedo threat and the ships mounted major-caliber guns.
The USS Maine mounted 2x2 10" turrets off-center on 57' 2.5". It also had no TDS. Later few USN ships (which mount 12"-16" guns) are also of similar dimensions.

It might be that Glorious/Courageous is in a similar situation but because I cannot find any cross-section or plan drawings for most British ships including this one, I can not determine. On the surface it seems there is beam to spare, but without the structural picture it is hard to say anything definitive with regard to minimizing the 80ft of beam.

We can also observe the design plans of historical battleships to see this effect. Because I happen to have a very good plan ( a Contract Plan!) on the South Dakota, let's examine it in some detail.
I've cropped and zoomed out so the relevant details are easier to see. On the left, we have amidship and to the right we have the forward turret.
If we exclude the TDS, which is represented by the layers on the side of the ship after of the forecastle, the actual width of the ship is is little less than half that of the total amidships beam. We can also see from the lack of flanges on the TDS layers and their presence on the rest of the ship that the TDS is not structural, i.e. it does not strengthening the ship. Indeed, this makes sense given the nature of the TDS is to absorb sudden buoyancy shocks, not withstand continual stress. We can conclude from this that given the South Dakota's ~108' ft of beam, we structurally need a little less than ~54' ft of beam to support a triple 3x16"/50 turret.

But there are a few problems with my argument:
1) I am ignoring the recoil force.
2) This is a technical argument, not a historical one and may be seen as less than satisfactory.
3) I am ignoring the machinery space.

The first problem is the reason why despite it being seeming possible mount a major-caliber turret on ~50 ft of beam, few ships that I know of has done so. This is because having a low beam width threatens stability due to the force from the ship's gun being enough to send the ship into an angle with a very low righting force, hence it capsizes. This is an argument to metacentric height and buoyancy. This is quite a strong argument given that KM which is the positive contributor to metacentric height (which is how SS calculates stability) is directly linearly proportional to Beam. Nothing else has such a large impact on stability. KG, which is the negative contributor to metacentric height is composed of the weight of various components and hence hard to control. I will discuss this at the meta-level soon.

The second problem is a nebulous counter-argument but one that people seem to favor. It draws some merit from the fact that I do not possess all the information regarding the designs I am drawing conclusions from. Hence it is very possible that I am completely wrong. That said it is inappropriate to address this currently, I will address this issue in the next section of my response.

The third problem attacks the issue differently than the original premise, which was that turrets can't be supported on low beam widths. Instead it reframes the debate and is liable to win it. If we look again at the South Dakota plan and indeed any other plan, the largest consumer of structural beam (i.e. structural supported beam, not including TDS) is the machinery spaces, not the turret. I think you may be aware of the great debates within historical designs about the switching between several different types of machinery and the different increases in beam associated with them. Indeed, one example that comes to mind is that of the P-class design discussions where it was noted that an switch from steam to diesel engines would result in an increase of 2m (6.6 ft) of beam.

Here is the picture of the South Dakota with regard to this issue:
I'll reiterate, notice how the TDS is not structural but the internal area is. We can see similar things in the cross-sections of other ships.

Let's look at another ship, this time a non-capital ship, the HMS Belfast (Alas I would put from other books such as Friedman's cruiser book, but it is the only one in the series that I do not have, these sparing few will have to make do).
This the tail section at the deepest level (double bottom and holds). As we can see the structural width of the turrets themselves is tiny. They occupy roughly 1/2.5 of the maximum waterline beam which is 63.33 ft (19.3m). Note the outline to the sides is depicting the upper level, given this is the level of the propellers. This implies a structural space of ~25 ft, quite thin! These are 3x6" RN turrets, which the previous data from Warships1 cited as having a diameter of 23.5 ft which means a margin of ~2 ft at minimum. A 15" turret would be roughly 33% wider. The margin itself will probably need to increase but even then it won't be by much. We see this in the South Dakota plan.

Why are there so few historical designs of such a nature? I've examined this question a little on the technical side of things and will proceed to explain it on the meta-level.
We have to keep in mind that naval architects from previous eras do not have the knowledge or tools we have today. Whilst this may seem obvious, the actual difference is quite surprising. Most of the theories and calculations I mention were produced in the 1970-1980s period and was completely unknown in the 1930-1950s. For example, the interactions of fluids with regard to fluid flow and seakeeping was practically not understood at all. This is most noticeable in the design failure of the North Carolina, South Dakota, and Iowa class with their skew design. This skew design alone prevented the former two classes from operating at full speed without severe vibration and dramatic decrease in seakeeping. The latter was only fixed after much much pain.

The naval architects of the past did not have the profound knowledge we have today in this regard. If they made a mistake, then as today, the loss would be tremendous. Hence they tended to not push the envelope. Whilst it could be possible to design a ship with 50ft of beam to support a triple turret, it would run the risk of design error and capsizing. It is much better to design a ship with much more beam than necessary than to be minimalist. Another meta reason for why beams were so large was hydrodynamic efficiency. It was not known how different design params would affect hydrodynamic efficiency hence designers did not like making new hull shapes and stuck to scaling up ships. We can see this in the P-class design discussions in which beams and lengths were tied together and scaled proportionally to keep hydrodynamic efficiency of the Deutschland-class.

Quoted

I think that your target reach figures does not take into account the complete suicide aspect of taking that ship so close to shore or into fairly restricted areas such as the Inland, Bohol, Visayan or Sibuyan Seas, or Kattegat. I think that the number of AA guns and the size of the CAP will have to be massive. Due to the proximity to the coastline, you can expect every plane to be heading your way.

To get at everything in Denmark, you'd have to go through fairly narrow straits where even people with portable rocket launchers would probably be shooting at your ships. Other nasty surprises in such traps would be shore mounted torpedo tubes, massive amounts of MTBs and midget subs. I can also see truck-mounted rockets being fired at those ships as well. If you have 100 MTBs and midget subs in that trap, each carrying 2 torpedoes, you'll have 200 torpedoes in the water and only two are needed to sink that cruiser (and due to the confined space, I would think that quite a few escort ships will bite the dust as well).

If the captain is smart enough, he'd stay far away from such areas.

I think you severely underestimate how much range 65km is. There are a few places where the ship would actually have to be close to the shore to reach a target inland, but those are few and usually low value anyways. Let's take each situation and I'll expound on the details:

Philippines:
65km means the ability to completely cover Palawan from 30-45 km off the coast
It means the ability to fire into the heart of Manila 10km off of Corregidor Island, that is 10km outside the Manila Bay. Not recommended, but one can avoid the bay entirely.
~50% of the land mass in the Sibuyan Seas can be reached from outside the Sibuyan Sea. The unreachable islands without entering the sea are not really that large and important.
Visayan Sea is a fair bit tricky, I'll admit. However you can still hit most targets from a safe distance away (10km >). The regions not really reachable without entering the sea is Cebu, Western Leyte, Western Samar, Eastern Negros Occidental & Oriental, and Bohol.
As for Bohol Sea, Zamboanga Del Norte & Sur can be covered completely from 20km off coast. Davao city can be reached 30-40km off coast but that's 55km inside of Davao Gulf. Still these are not tiny distances. There's really only two regions that can't be reached without maintaining 10km > off coast distance in Bohol Seas, they are Misamis Oriental and Bukidnon.

To be fair, Denmark indeed can't be all reached without entering the Kattegat, but the ship doesn't have to be close to the coast to reach all of Denmark if it can enter Kattegat... or at least 98% of Denmark. At it's thickest Denmark is 170km, most areas are much thinner on the order of 70km. For example, Aars can be reached 23km off coast north of Jammerbugten. Aalborg can be reached 35km off the coast on either side. Copenhagen can be reached from a ship in port at Beddingestrand or Angelholm.

I guess the issue here is choice of words. Indeed to reach ALL the targets I mentioned some would have to be <10km off the coast, but for most of them, and indeed the high valued ones can still be reached from quite a distance. We have to understand whilst this may seem surprising, 65km range is over 50% more range than the maximum ranges of a 18"/16" gun and well over the accurate range of such guns. Given that even today the ranges for shoulder-mounted missiles is 5km at best, I would say your assertion is quite bold.

It should be kept in mind that most torpedoes of WW2 have ranges of 8km and even the famed long lances have only a range of 40km which it would be moving at 36kts. For the later design, if the torpedo was to have a race with the ship, the ship would outrun it! Given the relative speed and distances, it would be quite easy for the ship to simply start to move away from the coast to be outside of the torpedo's range by the time the torpedo approaches. Since I mentioned most targets can be hit from 20km off coast, the speed required for that range for torpedoes and the speed of the ship itself makes getting a hit quite absurd.

I also think the submarine threat is quite overstated. It is extremely difficult for a submarine to approach firing distance with a destroyer squadron, especially if the destroyer squadron isn't moving very rapidly. The destroyers will detect the submarine via sonar long before the submarine is in firing range. I could expound on that a little more but I'm quite certain we are all aware of the discussion. Submarines are not military vessel hunters, when it happens, it's usually due to chance and good luck on the submarine's side. It's not a feasible proposition to expect to sink organized enemy battle groups by sending submarines at them.

Nevertheless, the threat of MTBs and torpedoes is the reason why I personally favor the second design. It is a much faster ship, 37.5kt, on a much longer tonnage. MTB threat is also overstated due to the accuracy of a battle group. The speed advantage of the MTBs, which is the crux of an MTBs success is almost nonexistent and so is the chance of such an operation's success.

Now if we assume destroyers can take 16 5" hits before being in a sinking position (according to SS), and notice that there is NO speed advantage here even with the fastest destroyers in Wesworld. Well... let's say that you can sit and wait all day till the cows come home and it won't be happening.

Of course that wasn't your argument. I am just making the point for reference since usually the scenario in question is that of destroyers attacking a battleline. Your argument was that of MTBs attacking the battle line. Let's assume a MTB speed of 40 knots, in reality this is wildly optimistic but let's go with it regardless. With a 2.5 knot (1.29 m/s) advantage it'll take 6201.55 seconds (103.36 minutes) to close the distance on a straight path. In that time ~248,000 100mm rounds could have been fired. If there is only a 0.05% hit rate (excessively low estimate) and only one 100mm round is needed to sink a MTB, then you'll need to send somewhere in the vicinity of 1240 MTBs to sink the ship by itself. Just coordinating that effort makes the scenario unfeasible. Of course, I should mention this is only because the ship is very fast at 37.5 knots and has a very heavy secondary battery, if it were a slower speed in the vicinity of 30 knots and had a battery of 10x100mm instead, the time to close would drop to 25.8 minutes and the volume of fire drops to 15,480 rounds, requiring 78 MTBs to pull off.

Now the airplane threat is quite real but I think there a two-fold problem with that line of argument.
The first is a meta-level issue: in Wesworld no nation has really had experience with aircraft's sinking capital ships, the Pacific War never happened. Yet we tend to assume it did! In Wesworld I don't believe there's a real reason to rate the aircraft threat so highly.
The second is a bit more complex and shows up whenever we try to try of military systems as isolated when they're not. First, a ship with 65km can conduct Runway Catering to great effect. Most airfields for the purpose of sealane interdiction are located along or slightly inland of the coast which can be easily bombarded by the ship without return coastal fire. Also a battlegroup with this ship does have significant AA firepower. The ship itself has 40x100m automatics! which is ~4 times more than other ships in it's weight class. There is also the doctrinal counter-argument to your point: A mass of aircrafts aiming to intercept this ship (which is very light tonnage ship by the way) which is not a slow ship either, represents forces tied up which can't be allocated to the land campaign. After all this is a ship with some 5x more raw AA firepower than many carriers and even a much higher AA fire rate than such historical capital ships.

To be more precise about this, I'll offer this snippet from the Antiaircraft Action Summary from Okinawa.
Now I'll do some calculations. I'll take the Iowa, South Dakota, North Carolina, etc. classes as a base: 20x5"/38 battery. For the purposes of this calculation, I'll use the French 100mm/55 Model 1953 gun as the equivalent of the 100mm automatic in the design. From these two guns I'll extract the rates of fire (using their lowest number) and attempt to conjure up an estimate on the effectiveness of the ship's AA.

5"/38 -> ROF: 15-22
100mm/55 -> ROF: 60-78

The 100mm will put in the air roughly 3 times more flak than the 5" will. If we hold that the 100mm will also have VT ammunition, it should require 540-550 rounds to put down a non-suicidal plane. Using the higher figure, let's calculate the time needed to attain this number of rounds. For the 20x5"/38, 1.83 minutes. For the 40x100mm/55, 0.23 minutes. Since the two guns have rather similar ranges, we'll say they have the same amount of time to react. Let's take the TBD avenger as the plane approaching.

The plane's manual lists a sea level maximum speed of 205 knots, or 105 m/s. I'll assume the plane isn't maneuvering to dodge AA fire and is on a straight path to the ship even though in reality this would be the case and slow the approach of such planes considerably. The engagement range of the 5"/38 and 100mm/55 is ~12km. The torpedo bomber's drop off range is assumed to be 3km, the torpedo's max range being ~4km. Hence the bombers will cover the 8km of danger in 1.33 minutes.

Following this you'll need ~6 planes to have a slight chance of making a successful run. In reality this would probably be more like ~10 planes for a good run. By comparison you would need only 1 plane to generate a hit versus a 5"/38 ship.

Of course this assumes the ship is operating alone with is a faulty premise. That's what the latter graphic is for. We notice that the ratio of actual to expected kills is roughly 1x more than for battleships. In addition about 40% of planes shot down are destroyed by the target ship and each supporting ship is about 1/3 as effective as the target ship in defending the target ship. We can extrapolate from this an estimate of 12-16 required to down such a ship "by itself" and even more so if it has a battle group to protect it. You can see very quickly the AA ability becomes enough to match a fleet carrier. It seems in more ways than one, the effectiveness of aircraft is overstated!

If we looked into the Pacific war, we notice practically all the losts were on ships with less effective AA platforms and ammunitions and even then it took dozens to sink fast ships which could avoid most hits. In the current Wesworld climate, that is without the experience of the Pacific War to mark the airplane as a win in naval engagements as well as the introduce of automatics, the effectiveness of aerial assault is even less significant. Until the introduce of anti-ship missiles, most other weapons, guided or not, have less range than 4km and as such the calculations still apply. That is, Wesworld seems to have skipped the intermediate era between the era of big guns and missiles in which aircrafts were dominant in naval engagements due to the introduction of automatic guns.

But I also think there is an issue here that inevitably crops up with these designs. That is, the tendency to think of these ships as a capital unit when clearly their tonnage says otherwise. This ship is not a capital ship but a cruiser not only in weight, but even doctrinally. They are not meant to fight other ships on the surface and hence I scratch my head on these lines of argument. These arguments of the ship being "sinkable" are subtly based on the premise that the ship is of such high value that sinking is not permitable. I would think losing a cruiser now and then, a 16,000 ton investment is not quite that big a deal, especially with destroyers in the 3,000-4,000 ton range. Is the loss of 4 destroyers worth of tonnage a huge blow to the fleet, especially since the loss comes rarely due to speed and range?

Quoted

To employ such a vessel would demand prior control of the air and sea surrounding the intended target area, obtained by more conventional means. If control of the air and sea have already been obtained, such a vessel is rather superfluous.

I mentioned above in my response to Walter that one does not need to be particular close to the target in order to reach in. In fact, such a ship can reach targets far beyond conventional means. Battleships with 16"/18" guns have maximum ranges of 38-42km but the engagement range where there is any semblance of accuracy in surface action is closer to 30km. In light of this, a range of 65km is enough to fire over two battleship engagement ranges, so to speak. That is not even counting the engagement ranges of smaller combatants which are usually <20km at best.

At the same time, the problems with conventional means of fire support have been expounded in the US NGFS debate multiple times. The issues even more apparent in Wesworld's era than the modern debate. Aircrafts have limited loiter time which greatly reduces the sorts of missions they can do, in addition pilots are expensive in time and money to train and the dogfights are high-casualty engagements. Aircrafts in this era also have many problems with night operations. Hence the role of the aircraft in fire support is actually quite limited in this era. Missiles don't even really exist yet so they aren't on the table. As a result, the ship and it's intended mission do carve out a unique niche which can't really be filled by conventional means. Aircrafts simply can't do the job of artillery. Artillery simply can't bring the same weight to bear with the same mobility and ROF. Other surface ships don't have the range or expendability to engage in the mission. They would suffer from being so close to the shore as to be hit by shoulder-mounted rocket launchers, as Walter said.

This does not mean that the ship itself cannot be bested by another design. It just means the role itself is not fulfilled by conventional means. The niche itself will soon die out with the advent of anti-ship missiles until the introduction of more advanced propellants and metallurgy in the modern but to discard the niche on that basis would be an argument from hindsight bias.

This is section 2, where I will basically throw away what I said previously and write down what I actually intend to do with the design given the feedback received.

1) Keep the speed at 37.5 knots or higher. The discussion and calculations on MTBs and Destroyer revealed how important to survivability speed is in this niche mission.
2) Keep the secondary battery of 100mm automatics at 40 or higher. Perhaps increase to 130mm automatics. Given the risks posed by airfield based aircraft, I would want (ideally) the capability to down a fleet carrier's air complement by itself. The ship can also find an auxiliary as AA cruiser for carrier fleets, given it will be much faster than the carriers it accompanies. (Following Walter's suggestion of the need of such heavy anti-MTB and AA capabilities)
3) Reduce the ship's displacement. Clearly even 16,000 tons is too much of an investment to stomach, hence I will attempt to drop the ship to ~12,000 tons or the equivalent of a light cruiser.
4) Reduce the ship's armor. Although it is already thin, the speed and range of it's guns as well as the presence of a battle group to escort it means it doesn't really need armor to complete it's mission. This is weight that could be saved.
5) Investigate possible weight savings in main armament whether by reducing the caliber without dropping the range or even increasing the range, or by reducing the number of barrels. Of course this is without resorting to sabots and other too-advanced methods.
6) Increase the ship's beam if keeping the same 380mm triple. (Following Brock's concerns)

Quoted

I think you severely underestimate how much range 65km is.

Well, I use Google Earth to look at distances so it's hard to see how I can underestimate the range. More likely a matter of definition of target. To me an airfield is as much a target as a farmer's opium corn field.

Kure, Kobe, Osaka are a few targets you can't reach unless you risk your ship into really dangerous enclosed waters.

Quoted

It should be kept in mind that most torpedoes of WW2 have ranges of 8km and even the famed long lances have only a range of 40km which it would be moving at 36kts.
...
...
...
The speed advantage of the MTBs, which is the crux of an MTBs success is almost nonexistent and so is the chance of such an operation's success.

With "such traps" I was talking about attacks in narrow stretches of water like the one between Kattegat and Fehmarnbelt. I was not talking about attacks on the open sea.

Launching from both sides, even the 8km ranged torpedoes are more than enough to get to your ships in various parts of that section on both sides. Long Lances would be overkill there. There is no need to torpedo the truck on the opposite shore.

Also with that example, the midget submarines are not "military vessel hunters". They're expendable "waiting for the foolish military vessels to enter the narrow strait trap" vessels.

Same would be true for the MTBs. The 6201.55 seconds figure can be chucked out of the window the moment the ships 'walk' into the trap. The MTBs will be waiting and jump out in front of you, not behind you, so there is no need to catch up with the ships. There is also a good chance that, due to the narrow space, the MTBs will already have launched their torpedoes when they are hit. 1240 MTBs would be seriously overkill with 2480 torpedoes being fired at your ships in that trap. There's even a very good chance of a torpedo torpedoeing a torpedo.

WalterYou're right, and I never addressed it but Japan's inland seas are hard areas to venture without substantially increasing the risk as you suggest. My main point is, however, barring such locations, almost all valuable targets can be reached with 65km of range. The threat faced by such a ship as the one prescribed with not face substantially less well as compared to other ships, in fact, much better than many of it's contemporaries.

In addition in the Denmark Straits, I presume the enemy is someone who owns one side of the strait (who else would be a potential enemy of Denmark?). I demonstrated some of the major targets in Denmark can be shot from within the safety of an allied port. The advantage over artillery piece in this case is the ability to relocate after your forces manage to take over said bombardment locations. With the example of Copenhagen, Copenhagen can be bombarded from port in Sweden. Once Copenhagen is taken the rest of the island can pretty much be cover from within Copenhagen port. From Naestved you can hit Nyborg and Svendborg and it is possible to continue this sort of port-hopping strategy to deal with the problem of threats within a Strait. Something similar is possible from Kiel.

Why is this operational mobility so important? I'll compare with other large artillery pieces of the era such as the Schwerer Gustav. Whilst the Schwerer Gustav fires a much much heavier round and is thus much more deadly, it is also very slow firing (14 rounds a day) has much less range (38-47km) and is constrained by rail and land travel. The gun required 3 weeks to put into firing position and needed to be moved by 25 railway cars. That's not even to consider the idea of moving across a channel/strait to another location. The Little David mortar was much more mobile but has a range of only 9.7km and still needs 12 hours to set up. The kill and casualty radius of major-caliber shells as compared to smaller shells is another reason for such a niche role.

Now the problem with your prescribed situation of surprise is that it assumes the ship will be operating close to the shore. As I've shown with the figures, that's completely unnecessary. Most targets can be hit from 20km and further off-shore or within the safety of an allied port. It would be pretty hard to "surprise" a battle group from the distance with some MTBs. In addition, torpedoes are utterly inaccurate are at any range larger than 4km. One need look no further than the afteraction reports of the Pacific War. Pretty much any maneuver will result is a torpedo miss, even a huge salvo of torpedoes. Again I stress I don't understand the situations you try to place the ships in... what are you trying to demonstrate? What you have said about the possibility of such a ship being sinkable due to submarines and MTB is no different than that of any other ship. If the decision is to overbuild MTBs to counter a niche ship which has auxiliary functions, other ships now have more operational flexibility. Not to mention I am not advocating the use of this ship in narrow straits and in many ships such a situation is completely unnecessary.

To sharpen the focus, the ship is meant to be a complement to the army's axis of advance. Hence by doctrine there is implicit the presence of a convention land force. The firepower of a large-caliber gun means general bombardment such as the bombardment of a fortified position can be accomplished more effectively and with far fewer ammunition. In addition the lack of ammunition consumption on the part of the land forces means the land force has more rounds to spare during a firefight which also eases the logistics of the army and alleviates part of the limit due to resupplying on the speed of the army's advance. The ship is an artillery piece that sacrifices safety and some accuracy in exchange for operational mobility, which is a huge benefit IMO.

Quoted

That's probably true, I just defaulted to the quads because I like the look of quads. I can see the same armament with more mounts given the latter design has only 1 forward turret, leaving the entire amidships and aft section free for such mounts. I'll make a note to turn the quads into twins in the rework.

So it's basically a high-speed monitor, a concept I've occasionally tinkered with but never seriously put forward...

...except that 12" armed destroyer I suggested in Navalism once.

The ship has reach, but what sort of accuracy will be expected at longer ranges? Hitting a bunker would seem to be a long shot, while hitting enemy front-line positions would risk blue-on-blue "unders".

The other question that comes to mind: Is the high speed a "sprint" speed for rapid reaction (either to or away from something) or is it the default operating speed of the vessel?

The number of shells per main gun seems quite low and will demand replenishment quite often, for which the ship will be forced to retreat into saver waters. Transit and replenishment time will cost you time for your prime mission. I think this is an issue.

An interesting idea, but wouldn't it just be easier to park an old battleship offshore? An old Royal Sovereign or Queen Elizabeth offers much superior firepower and armoured protection. In 1939 Churchill had the idea to take an R and remove two 15in turrets and fit massive bulges for use as a monitor in the Baltic.

Also, those automatic 100mm guns would be almost impossible to achieve, the feed system would be far too complex and the size of the turrets would be immense, probably equal to a triple 6in or slightly larger.

If the enemy launches a raid with a battleship, and you're using an R or QE for bombardment, the R or QE has to stay and fight - but it can buy time for all the transports, landing ships, and small escorts to flee.

If the enemy launches a raid with a battleship, and you're using a supermonitor for bombardment, the supermonitor has to flee - leaving all the transports, landing ships, and small escorts to be destroyed

Quoted

The number of shells per main gun seems quite low and will demand replenishment quite often, for which the ship will be forced to retreat into saver waters. Transit and replenishment time will cost you time for your prime mission. I think this is an issue.

On one hand that is true, but on the other hand, those 15" guns are not automatics. Still, it is good that you mentioned the number of shells because...

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One bigger problem with that number of main battery shells set at 100 is the number of shells per gun for all the other guns you will end up with because of SS's calculations. For your secondary 100mm guns, the magazine weight is (according to SS) ~85 tons when set to 100 shells per gun. If you enter the 100mm as the primary gun, you'll get 125 shells per gun for a magazine of 85 tons. Having done various tests with SS in the past regarding shell numbers, I know that the 3rd, 4th and 5th guns have the same amount of shells as the 2nd gun so the extremely low number of shells for the 2nd, 3rd, and 4th guns would be a much, much bigger problem than the 100 shells for the 38cm guns because it will take two minutes before your air/surface defenses become ammoless and thus completely useless if we were to stick to the lower ROF value you gave of the French 100mm/55 and assume that the 100mm is the slowest firing weapon of the bunch.

In the beginning I used miscellaneous weights for additional shells, but more recently I decided to play around with the "Shells per gun, main battery" figure to get the correct number of shells per gun for the other gun slots as I believe that this is more proper.

SS2 is not like SS3 where you can individually enter the number of shells for each gun slot. If you want more shells for the 2nd-5th guns in SS you will either have to add miscellaneous weights or play around with the "Shells per gun, main battery".

Rock Doctor
Yes, basically it is a glorified Monitor
In general it is mean as a area bombardment. If the ship has a 1% of range pattern size at 65km, the pattern size will be ~650m. That's roughly double the size of a bridge but about the same size as an airfield. You could use it to make certain routes of reinforcement very difficult to use as well as to disable nearby airfield. Other uses may be to destroy most of a city before moving in with forces to reduce the defensibility of the city.

My perceived usefulness of such bombardment is probably due to my propensity to use artillery as an area-denial weapon whenever wargaming.

The speed is as Walter states. Although that is how I intended the speed to be used. Looking back now the ship can also be used as an AA cruiser to escort fast carriers.

Walter
I did mention it was a 15"/56 which entails more muzzle velocity than the actual Bismarck gun. I determined the range from my tools and cross-checked with NAaB and NavGun. Perhaps a revision to 60km anyways?

Regarding the different amount of ammo per battery, that is indeed quite troubling. I'll try to adjust accordingly.

Hooman
That's a good catch, I'll have to up the number of shells in the rework. Any suggestions on a good amount?

Hood
It is just as Rock Doctor points out.
I mention in my premise for the design where I detailed what the potential threats the ship would face and the how I chose to respond to them. I chose a fast, lightly armored ship to keep displacement low. A R&QE battleship may also fill the role, but it's also quite a bit heavier tonnage-wise in comparison. Another point is that it's also slower so it reacts to MTB, destroyer, and submarine threats slower. The third issue is the much lighter AA battery, but that's really a non-issue with retrofitting of such batteries.

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